526 
The Right Honourable George Knox 
OBSERVATIONS. 
I do not mean to waste the time of the Royal Society, by 
applying the facts above stated to confirm, or invalidate, 
either of the great rival theories ; still less to support any 
hypothesis of my own. 
A most instructive lesson has been inculcated by the recent 
discoveries of Sir Humphry Davy, in his examination of the 
cavities of crystals. In that ingenious Paper, a fact, which 
had for many years been considered as evidence almost con- 
clusive in favour of one system, has been converted into an 
argument nearly irresistible in support of the other. I shall 
confine myself, therefore, to calling the attention of the So- 
ciety to some of the most obvious results and inferences. 
It may be a question, whether the bitumen obtained by 
distillation, has actually existed in the stone. That it may 
have been somewhat altered, or contaminated in the process, 
is not improbable ; but it is to be observed, that an inflam- 
mable oily substance, scarcely discernible from that which 
distils over, may be obtained in the common method of ana- 
lysis ; and likewise, that the bitumens obtained by distilla- 
tion from such a variety of earthy substances, possess the 
same smell, colour, and volatility. 
That the ammonia, however, which sometimes appears, is 
a product, and not an educt, I have myself little doubt ; and I 
trust, it is rendered highly probable by the experiments on 
felspar and bole. I conceive that it arises from the decompo- 
sition of the bitumen, either by the iron of the retort, or the 
carbon of the stone, at a high temperature. 
The manner in which pulverised stones, which are both 
